Hello Jochen, Thank you for your reply.
I have managed to install graylog successfuly and make it work. I will post details on how to upgrade on a centos6 ; I think it could be useful for someone else. Regards, -- You received this message because you are subscribed to the Google Groups "Graylog Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to graylog2+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/graylog2/4b6367da-72a7-4c7c-a523-c43ad4bfc04b%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
